The invention relates to a rudder for watercraft having a fin which can be rigidly locked to the main rudder, and an adjusting system for the fin which is disposed in the rudder engine space.
Rudders are disposed in the form of rotatable plates or displacement members on the stern of watercraft and when operated--i.e. when adjusted to a given rudder angle--produce a hydrodynamic transverse force which engages with the rudder and consequently with the end of the vessel, providing the steering force required to steer the vessel. The hydrodynamic transverse force produced by the rudder results in a rudder torque in relation to the pivoting axis of the rudder.
To produce high rudder transverse forces, two-part or multi-part rudders are known for use on vessels which require a high torque effect that occurs with rudders that are divided into several parts, particularly when the rear part of the rudder is adjusted in relation to the direction of the current more sharply than the front part of the rudder. Such constructions are known as high-performance rudders. In the case of multi-part high performance rudders of known construction the torque to be produced by the rudder engine is appreciably greater than in the case of a single-part displacement rudder of equal lateral area.
The known multi-part high performance rudders such as, for example, the BECKER-rudder, cannot be switched off. They make their high torque properties available not only when they are needed, namely for maneuvering at low speeds, but also at full operating speed. Due to the very high forces which are exerted on such a high performance rudder at relatively high speeds of the vessel, correspondingly strong connecting assemblies are required, namely the rudder stem, the rudder engine and the whole maritime connecting constructions at the stern.
It is therefore an object of the invention to provide a rudder having a fin for watercraft in which although, as in the prior art constructions fin adjustment can be constrainedly controlled by the movement of the main rudder, such constrained control can nevertheless be switched off; this is convenient more particularly at higher vessel speeds, to obviate the reinforced connecting assemblies otherwise needed. If required, the rudder can be converted into a single-part rudder.
A further condition for the rudder according to the invention is that all the elements which can be activated are easily accessible in the hull and not, as in certain prior art constructions, in the rudder blade, where they are constantly subjected to heavy loading due to vibration, icing, possible leaks and the like, and where they can neither be given maintenance nor repaired from the vessel if anything goes wrong.